Commonly Used Block Elements:

<address>
Contact information.
<blockquote>
Long ("block") quotation.
<div>
Document division.
<form>
Input form.
<textarea>
Defines a multiline input control (text area).
<h1>, <h2>, <h3>, <h4>, <h5>, <h6>
Heading levels 1-6.
<hr>
Horizontal rule (dividing line).
<iframe>
Defines an inline frame.
<p>
Paragraph.
<pre>
Preformatted text.
<table>
Table.
<tr>
Defines a row in a table.
<td>
Table cell.
<th>
Defines a header cell in a table.
<tfoot>
Table footer.
<ol>
Ordered list.
<ul>
Unordered list.
<li>
List item.
<dl>
Definition list.
<dt>
Defines a term (an item) in a definition list.
<dd>
Definition description.
<header>
HTML5 - Section or page header.
<hgroup>
HTML5 - Groups header information.
<section>
HTML5 - Section of a web page.
<article>
HTML5 - Article content.
<aside>
HTML5 - Aside content.
<figure>
HTML5 - Groups media content with a caption.
<figcaption>
HTML5 - Figure caption.
<footer>
HTML5 - Section or page footer.
<audio>
HTML5 - Audio player.
<video>
HTML5 - Video player.
<canvas>
HTML5 - Drawing canvas.

Commonly Used Inline Elements:

<em>
Defines emphasized text.
<strong>
Defines important text.
<sub>
Defines subscripted text.
<sup>
Defines superscripted text.
<i>
Defines a part of text in an alternate voice or mood.
<b>
Defines bold text.
**elemets that you should never use**
big, small, tt, strike, acronym
<a>
Defines a hyperlink.
<time>
HTML5 - Defines a date/time
<br>
Defines a single line break.
<img>
Defines an image.
<span>
Defines a section in a document.
<script>
Defines a client-side script.
<button>
Defines a clickable button.
<input>
Defines an input control.
<label>
Defines a label for an input element.
<select>
Defines a drop-down list.
<abbr>
Defines an abbreviation.
<q>
Defines a short quotation.
<cite>
Defines the title of a work.
<dfn>
Defines a definition term.
<kbd>
Defines keyboard input.
<samp>
Defines sample output from a computer program.
<code>
Defines a piece of computer code.
<var>
Defines a variable.